Proceedings.] DISCUSSION ON CITY AND SOUTH LONDON RAILWAY. 111 tested, the fact that at the stations about 2,000 feet in length of Mr. Greathead. the tunnels had been taken out was referred to in the Paper, and the perfect condition of the grouting behind the iron lining described. Within half-an-hour of its injection the grouting was generally as hard as the clay, and in a short time i t became much harder, andmit was therefore capable of taking the pressure transmitted by the clay. The cases

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... f damage to property on the railway had been occasioned by the construction of the brick-lined tunnels, and were not due to any enlarged iron tunnels. As regards pumping, the success of the system of tunnelling described was due to the avoidance of that source of expense and danger.